The Northern Mechanical/Plumbing Contractors Association is comprised of Signatory Contractors in the Plumbing/Mechanical, Sheet Metal, HVAC/R, Insulation and Roofing Industries. All of our contractors are signatory to local unions and pull their workforce from some of best trained unions in Minnesota. The following is a listing of the contractors that belong to The Northern Mechanical/Plumbing Contractors Association. There is no contract or wage information on this site. For contract or wage information, please contact the Associations Office.